Occurrence and management of faba bean necrotic yellows virus in food legume crops

Abstract

Faba bean necrotic yellows virus (FBNYV, genus Nanovirus, family Nanoviridae) causes an important disease of several food and fodder legumes. Its main symptoms are leaf yellowing, plant stunting, reddening, thickening of the leaves, and suppression of flowering and pod setting (Fig. 1A). These symptoms closely resemble those caused by luteoviruses (e.g. Bean leafroll virus) and proper diagnostic tools are essential to identify the correct causal agent. FBNYV is persistently transmitted by various aphid species, and most efficiently by Acyrthosiphon pisum and Aphis craccivora. FBNYV epidemics have been reported in several countries in West Asia and North Africa. A number of FBNYV epidemics on faba bean in Egypt during the 1990s had a dramatic impact on the rural economy of the affected regions (2). FBNYV does not occur in Australia. Because of its destructive potential, it has been classified as a major potential threat to the Australian food legume industry. Pre-emptive research is being carried out at ICARDA to evaluate the susceptibility of Australian varieties to infection with this virus. FBNYV is related to the Subterranean clover stunt virus (SCSV), a virus unique to Australia, which affects several pulse species. Such relatedness is currently under investigation in a collaborative project between ICARDA and Australian researchers.